Being disturbed, enter into custody (9)
I believe the answer is:
retention
'custody' is the definition.
(I've seen this before)
'being disturbed enter into' is the wordplay.
'being disturbed' indicates an anagram.
'enter'+'into'='enterinto'
'enterinto' is an anagram of 'RETENTION'.
(Other definitions for retention that I've seen before include "holding" , "Capacity to remember" , "Saving" , "Failure to eliminate a substance from the body" , "Keeping hold (of something)" .)